1. Field of the Invention
The present invention relates to a method for manufacturing a wiring over a substrate and a semiconductor device having a multi-wire structure.
2. Related Art
In recent years, a wiring over a substrate and a semiconductor device are highly integrated since the degree of integration of a semiconductor element is improved. Accordingly, the width of a wiring is further miniaturized, and the number of wirings is increased. Moreover, an area of the semiconductor device is reduced by being the wiring into multi-wire.
However, there is a problem of disconnection or short-circuiting of the wiring due to particles such as contaminant particles since the space between the wirings becomes narrowed due to the increase of the number of wirings.
In the semiconductor device having a multi-wire structure, the width of the wiring is miniaturized and the density of the wiring is increased, which leads that a difference in projection and depression is increased and the coverage of an insulating layer provided between wirings is deteriorated. Therefore, there is another problem that a lower wiring and an upper wiring are short-circuited.
In the case of forming an insulating layer over the wiring by a coating method, an insulating material is contracted and the stress is concentrated at the edge of the wiring when baking the insulating material. As a result, cracks are produced in the insulating layer, which results in another problem. The cracks in the insulating layer yields problems that irregularities are produced over the surface of the insulating layer; corrosion of the lower wiring due to penetration of moisture from the crack; and short-circuiting of the upper wiring and the lower wiring at the crack.
Further, particles remained between wirings also cause cracks and irregularities over the surface of the insulating layer. In the case of forming a light-emitting element over the insulating layer, an anode and a cathode of the light-emitting element are short-circuited, which leads to the deterioration of the light-emitting element.
When a crack is occurred in a certain portion of the insulating layer, cracks become readily occurred in another regions. That is, cracks become into a chain reaction. As a result, manufacturing yields of the wiring over a substrate and the semiconductor device are reduced.